期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 396, 期 3, 页码 719-731出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2009.12.001
关键词
analytical ultracentrifugation; assembly; coiled coil; glycerol spraying/rotary metal shadowing electron microscopy; intermediate filaments
资金
- European Commission [LSHM-CT-2005-018690]
- German-Israeli Foundation for Scientific Research and Development [915-111.13/2006]
- K.U. Leuven [/07/071]
- M. E. Muller foundation
- MHV-project [PMTDA-106174/1, 2004-2005]
Half-minilamins, representing amino- and carboxy-terminal fragments of human lamins A, B1 and B2 with a truncated central rod domain, were investigated for their ability to form distinct head-to-tail-type dimer complexes. This mode of interaction represents an essential step in the longitudinal assembly reaction exhibited by full-length lamin dimers. As determined by analytical ultracentrifugation, the amino-terminal fragments were soluble under low ionic strength conditions sedimenting with distinct profiles and s-values (1.6-1.8 S) indicating the formation of coiled-coil dimers. The smaller carboxy-terminal fragments were, except for lamin B2, largely insoluble under these conditions. However, after equimolar amounts of homotypic amino- and carboxy-terminal lamin fragments had been mixed in 4 M urea, upon subsequent renaturation the carboxyterminal fragments were completely rescued from precipitation and distinct soluble complexes with higher s-values (2.3-2.7 S) were obtained. From this behavior, we conclude that the amino- and carboxy-terminal coiled-coil dimers interact to form distinct oligomers (i.e. tetramers). Furthermore, a corresponding interaction occurred also between heterotypic pairs of A- and B-type lamin fragments. Hence, A-type lamin dimers may interact with B-type lamin dimers head-to-tail to yield linear polymers. These findings indicate that a lamin dimer principally has the freedom for a combinatorial head-to-tail association with all types of lamins, a property that might be of significant importance for the assembly of the nuclear lamina. Furthermore, we suggest that the head-to-tail interaction of the rod end domains represents a principal step in the assembly of cytoplasmic intermediate filament proteins too. (C) 2009 Elsevier Ltd. All rights reserved.
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